Blood vessel sizing device

ABSTRACT

Medical devices and methods for determining the size of blood vessels are disclosed. In one implementation, a blood vessel sizing device is configured for placement on an area of skin of a patient. The device includes a plurality of radiopaque concentric-circle elements. In one implementation, a blood vessel sizing method includes placing a marker having a plurality of concentric-circle elements on the skin of a patient, imaging a blood vessel of the patient and the device, and comparing the imaged blood vessel to the imaged circles to determine the blood vessel size, the concentric-circle elements allowing a determination of size without errors of parallax.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/427,084, which was filed on Mar. 22, 2012, entitled “BloodVessel Sizing Device,” which is incorporated herein by reference in itsentirety.

BACKGROUND

The present disclosure relates generally to medical devices and morespecifically to systems and methods for determining dimensions of imagedobjects on a graphical representation medical devices for determining ormeasuring blood vessel size during, for example, an angiogram.

Determining blood vessel size quickly and accurately is important, forexample, when treating stenotic vessels with angioplasty or stent. Ifblood vessel size is incorrectly determined, a stent that is too largefor the actual blood vessel size could be selected. Using an oversizedstent can damage, dissect or even perforate the passageway it isincluded to be filled within.

Diagnostic imaging using, for example, X-ray machines, computertomography machines or magnetic resonance imaging machines, generateimages of blood vessels including any narrowing of blood vessels. Aclinician uses these images to determine blood vessel size and stenosis.But using such images has inherent limitations. For example, computertomography imaging accuracy can be affected by sampling, size of displayfield of view and/or intravascular density of a contrast material.During emergency procedures, computer tomography or magnetic resonanceimaging measurements may not be available.

A need accordingly exists for medical devices and methods that improvethe process of determining blood vessel size during, for example,angiographic procedures.

SUMMARY

Aspects of the present disclosure relate to systems, devices, andmethods that provide a more accurate dimension (e.g., a length) of afeature represented in a graphical representation of an imaged object(e.g., an imaged body portion represented in a radiograph captured by aradiograph process. In one example, the present disclosure is directedto medical devices and methods that more accurately provide themeasurements of imaging targets. In one implementation, the devices andmethods described herein may be configured to determine blood vesselsizes with greater accuracy, based upon, for example, angiographicimages of the vessels. Such blood vessel images can be generated, forexample, via angiograms. In one implementation, a blood vessel sizingdevice is configured for placement on the skin of a patient near animaging target (e.g. a blood vessel to be imaged). Accordingly, thedevice may include a plurality of radiopaque concentric-circle elementsof known size. When a computer machine generates an angiographic imageof the blood vessel, the radiopaque concentric-circle elements cause thecircles to be visible on the generated image (along with the bloodvessel image). As such, a clinician may quickly and accurately determinethe actual size (true dimension/length) of the blood vessel by comparingthe blood vessel image to the image of the concentric circles, whichhave a known or illustrated dimension.

In one aspect, the systems and methods described herein include a bloodvessel sizing device having a rigid planar base structure with a frontsurface and a back surface. The blood vessel sizing device further has aplurality of radiopaque concentric-circle elements and a plurality ofradiopaque symbols positioned on the front surface of the basestructure. Additionally, the device has a deformable structure attachedto the back surface of the base structure, and an adhesive layerattached to a back surface of the deformable structure.

In another aspect, a blood vessel sizing device is described as having arigid planar base structure with a plurality of radiopaqueconcentric-circle elements positioned on a front surface. Additionally,the front surface of the base structure has a plurality of radiopaquesymbols representing dimensions of the concentric-circle elements.

In yet another aspect, a non-transitory computer-readable mediumcomprising computer-executable instructions is described for automateddetermination of a true dimension of a biological feature present in aradiological image. The instructions include receiving datacorresponding to a biological feature in a radiological image,determining a length property of the biological feature, and identifyingelements from image data last corresponds to radiopaqueconcentric-circle elements of known size. The instructions furtherinclude identifying dimensional properties for the identified elements,determining a longest axis of the identified concentric-circle elements,and comparing the length property of the biological feature to theconcentric-circle elements along the longest axis. Subsequently, thedetermined length property may be converted into a true dimension value,and communicated to a user.

It is accordingly an advantage of the present disclosure to provide amedical device that simplifies and improves blood vessel sizedetermination, and without errors of parallax

It is a further advantage of the present disclosure to provide a methodfor improving the process for blood vessel size determination.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of a blood vessel sizing device.

FIG. 2 is a plan view of an alternative implementation of a blood vesselsizing device.

FIG. 3A-3B depicts alternative implementations of blood vessel sizingdevices.

FIG. 4A-4B schematically depict side views of blood vessel sizingdevices.

FIG. 5A-5B schematically depict side views of alternativeimplementations of blood vessel sizing devices having deformablestructures.

FIG. 6A-6B schematically depict radiographic images produced by bloodvessel sizing devices.

FIG. 7 schematically depicts a radiological image including one or morebiological features.

FIG. 8 is a schematic block diagram of an imaging system.

FIG. 9 is a flowchart diagram of one or more processes for automaticallydetermining a true dimension of a future captured in a radiologicalimage.

FIG. 10A-10B schematically depict a blood vessel sizing device beingused on a human patient.

FIGS. 11A-11D schematically depict various implementations of a devicethat may be utilized for locating an area of interest within aradiological image.

DETAILED DESCRIPTION

In one example, the present disclosure is directed to medical devicesand methods that allow more accurate determinations of one or moredimensions (e.g., length, height, depth) of target objects targeted tobe captured by an imaging technique. Such target objects may includebiological features, e.g. living passageways (such as blood vessels),items within living passageways (e.g., blood clots), and/or any objectthat may be imaged with one or more imaging techniques. Yet, otherembodiments may capture one or more objects in a target area that istargeted by an image technique. Using a medical example, a user may beexperiencing pain in a general or specific area of their body.Therefore, it may be desired to utilize an imaging device to capture animage of the area without specifically targeting a specific object orfeature. Thus, the device may be configured to capture a target areawith one or more objects of interest.

The terms “graphical representation” and “image” are used herein torefer to an output of an imaging technique. Such imaging techniques thatgenerate the graphical representations/images may include one or moreprocesses (which may not be mutually exclusive, and may be combined withother processes, including non-image based processes), to provide anoutput comprising a graphical representation or image of a target areaand/or target object, including an angiogram, MRI, X-Ray, CT scan,myelogram, thermograph, MRN, ultrasound, and/or combinations thereof orother mechanisms that can produce a graphical representation or image ofa target object or target area. Further, those of ordinary skill in theart will readily appreciate that the systems and methods describedherein may be utilized for non-biological purposes (e.g. for imaging ofsynthetic materials, and the like), and without departing from thedisclosures herein.

FIG. 1 schematically depicts a device 100 configured for providing amechanism to determine one or more dimensions of features in a graphicalrepresentation of an imaged object or area. In one implementation,device 100 may be configured to be placed in an area to be imaged, suchas, contact with an area of skin of a patient prior to a medical imagingprocedure, and such—device 100 may be utilized to determine a truedimension/length of one or more biological features to be imaged usingan imaging technique (e.g. an angiogram using x-rays, and the like).

In particular, device 100 may comprise a base structure 102. Positionedon the base structure 102 or another surface are shown a pluralityconcentric-circle elements, numbered as elements 104 a-104 h, and aplurality symbols, numbered as symbols 106 a-106 g and 107 a-107 g. Inone example, the elements 104 a-104 h, and symbols 106 a-106 g and 107a-107 g, may comprise a radiopaque (radiodense) metal, a radiopaquealloy, or another radiopaque material known to those of ordinary skillin the art, and wherein radiopacity will be readily understood to thoseof ordinary skill in the art as a property of a material thatsubstantially reduces and/or prevents electromagnetic radiation of acertain wavelength/range of wavelengths from passing through thematerial. In particular, radiopacity may be understood as a property ofa material that substantially reduces and/or prevents x-rays frompassing through the material. In yet other embodiments, materials thatare reactive to certain imaging techniques or chemical processes mayalso be utilized. In this regard, the elements and symbols herein(including elements 104, symbols 106 and/or 107) may be configured toreduce or prevent transmission of wavelengths such as to appear opaque.In yet other embodiments, they may contain materials known to contrastwith an intended target object or target area, such as would be similarto the use of contrast agents in radiological sciences. In yet anotherembodiment, at least one element and/or symbol may comprise a materialthat is configured to be fluoresce as a result of being imaged or somemechanism utilized prior to or during the imaging process(es).

In one example, one or more of elements 104 a-104 h and/or symbols 106a-106 g may be provided directly, e.g., printed, onto base structure 102using, e.g. any appropriate printing method known to those of ordinaryskill in the art. In other examples, one or more of elements 104 a-104 hand/or symbols 106 a-106 g and 107 a-107 g may be molded into basestructure 102, fastened to base structure 102 by any appropriatefastener, or adhered/welded to base structure 102, and the like.

In one example, base structure 102 may comprise one or more of apolymeric material, a glass, a metal, an alloy, or any other materialwith material properties that give rise to a contrast between basestructure 102 and one or more of elements 104 a-104 h, symbols 106 a-106g and 107 a-107 g, and/or location marker 108 when imaged usingelectronic radiation of a particular wavelength/range of wavelengths(e.g., x-rays). In one example, base structure 102 may comprise apolymer that is substantially transparent to electromagnetic radiationin the visible spectrum (e.g. visible light). As discussed above,certain elements (104) or symbols (106,107) may be configured to beopaque and/or react to different imaging processes.

In one implementation, base structure 102 may comprise a material withmechanical properties exhibiting a level of rigidity such that basestructure 102 does not readily conform to one or more undulations of asurface onto which it is positioned. In one example, this rigidity maybe achieved by selecting base structure 102 with a material thicknesscorresponding to an appropriate level of rigidity. Specifically, in oneexample, base structure 102 may comprise a polymeric material with athickness of 0.25 mm, 0.5 mm, 0.75 mm, 0.9 mm, among many others.

In one implementation, concentric-circle elements 104 a-104 h may haveknown diameters. In one example, the diameters of the elements 104 a-104h may measure 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 14 mm, 16 mm, 20 mm or 30mm. However, as will be readily apparent to those of ordinary skill inthe art, differently sized concentric-circle elements 104 a-104 h may beused without departing from the scope of this disclosure. Furthermore, adifferent number of elements than those eight elements represented as104 a-104 h may be used on device 100 without departing from the scopeof this disclosure. In one example, elements 104 a-104 h may have athickness (line thickness) of approximately 0.25 mm, and wherein thediameter of each of the elements 104 a-104 h is measured to the centerof the radiopaque line that makes up each of the elements 104 a-104 h.In one implementation, and as depicted in FIG. 1, one or more symbols(e.g., symbols 106 a-106 g and/or 107 a-107 g) may intersect one or moreof the elements 104 a-104 g. In this way, a symbol may serve as anindicator of a dimensional property of a element with which itintersects. For example, a symbol may denote a radius or diameter of aconcentric-circle elements with which it intersects. In another example,a symbol may not intersect with a element for which it denotes adimensional property. In the specific example depicted FIG. 1, aplurality of symbols denote a plurality of diameters of respectiveconcentric-circle elements. Specifically, symbols 106 a and 107 a areshown as being diametrically opposed on the concentric-circle element104 b, and indicate that concentric-circle element 104 b has a diameterof 4 mm. Similarly, symbols 106 b and 107 b indicate thatconcentric-circle element 104 c has a diameter of 6 mm; symbols 106 cand 107 c indicate that concentric-circle element 104 d has a diameterof 8 mm; symbols 106 d and 107 d indicate that concentric-circleelements 104 e has a diameter of 10 mm; symbols 106 e and 107 e indicatethat concentric-circle element 104 f has a diameter of 14 mm; symbols106 f and 107 f indicate that concentric-circle element 104 g has adiameter of 16 mm; and symbols 106 g and 107 g indicate thatconcentric-circle element 104 h has a diameter of 20 mm. Yet in anotherembodiment, one or more elements may have a diameter of 30 mm.

In one example, and as depicted in FIG. 1, symbols 106 a-106 g areembodied as numerals (e.g. Arabic numerals). Those of ordinary skill inthe art, however, will readily understand that any symbol may be used todenote a dimensional property (e.g., a diameter) of one or more ofconcentric-circle elements 104 a-104 h. for example, symbols 106 a-106 gmay be computer-readable shapes and/or patterns (e.g. barcodes, and thelike). Indeed, in certain embodiments, a symbol or marker may providecomputer-readable indicia that may be detected (including automatically)before, during, or after an imaging process. In certain embodiments, thesymbol or indicia may not readily convey the dimensional propertyrepresented without prior knowledge to its correlation to thedimensional property.

In one implementation, device 100 has a location marker 108, whereinlocation marker 108. Location marker, like the elements and symbolsdescribed herein, may comprise a radiopaque area, contrast materials,and/or fluorescent materials. In one implementation, location marker 108has a surface area of between 18 and 22 mm². Location marker 108 may bedistanced a predetermined distance from at least one or more of elements104, symbols 106 and/or symbols 107. In one embodiment, the diameter ofthe a concentric circle, such as circle 104 h, may be less than, equalto, or larger than the distance from location marker to that circle, thecenter of the concentric circles 104 a, or another location associatedwith the circles 104 or symbols 106/107. In yet another embodiment, adimension (e.g., diameter) of marker 108 may be proportional to one ormore aspects of the circles 104, and/or symbols 106/107.

In one example, electromagnetic radiation of a certain wavelength (e.g.x-rays) may not pass through, and/or the transmission of the radiationmay be substantially attenuated through elements 104 a-104 h, symbols106 a-106 g and 107 a-107 g, and/or location marker 108. Accordingly, aradiological image (otherwise referred to as a radiograph, or x-ray, andthe like) of a biological and/or synthetic feature may include arepresentation or image corresponding to one or more of elements 104a-104 h, symbols 106 a-106 g and 107 a-107 g, and location marker 108.

In one implementation, location of one or more of elements 104 a-104 h,and/or symbols 106 a-106 g and 107 a-107 g may be aided by locationmarker 108, wherein location marker 108 has a comparatively largerradiopaque surface area than anyone element 104 a-104 h or symbol 106a-106 g or 107 a-107 g. As such, the comparatively larger radiopaquesurface area of location marker 108 may correspond to a larger featurewithin a radiological image produced using device 100. Accordingly,location marker 108 may be relatively more visible to a user, and hence,more quickly recognized in a produced radiological image. One or more ofelements 104, symbols 106/107, and/or marker 108 may be configured tohave a first appearance when imaged under a first imaging process andsecond appearance when imaged under a second image process. This may bebeneficial for a few reasons. In one embodiment, it may allow thedetection of whether the proper procedure was used, and/or what type ofprocedure was used. In one embodiment, the first appearance may beconfigured to present itself on a graphical representation when a firstwavelength was used and the second appearance may be associated with asecond wavelength, such as one that may be erroneously used for aspecific instance.

FIG. 1 depicts device 100 having base structure 102 with an outerperimeter 103 having a discrete shape. Those of ordinary skill in theart will recognize that base structure 102 (and/or entire device 100)may have any shape, and without departing from the scope of thisdisclosure. In this way, one alternative implementation of device 200 isdepicted in FIG. 2.

FIG. 2 depicts device 200, which may be similar in one or more aspectsto device 100 from FIG. 1. In particular, device 200 has a basestructure 202 that may be similar in structural features to basestructure 102 from FIG. 1. In this example, base structure 202 isembodied with outer perimeter 210, which exhibits a different shape thanouter perimeter 103 of device 100. Device 200 further includes a scale206 located thereon. In one example, scale 206 may comprise one or moreelements like or similar to elements 104 a-104 h and/or symbols 106a-106 g and 107 a-107 g from FIG. 1, including in relation to one ormore of their quantity, size, shape, proportional dimensions, radioopacity, and combinations thereof. Further, location marker 208 may besimilar (in terms of dimension, location, and/or other attributes, suchas those described above) to location marker 108 from FIG. 1.

One or more devices, such as devices 100 or 200, may include a uniqueidentifier. In one example, device 200 comprises a unique identifier212. Unique identifier 212 may be provided, e.g., printed, onto basestructure 202. In one specific example, unique identifier 212 maycomprise a radiopaque material. In one example, unique identifier 212may be used to associate one or more data points with device 200. Forexample, unique identifier 212 may be used to identify a patient imagedusing device 200 (e.g. to produce, in one example, an x-ray), thespecific imaging equipment, personnel employing the imaging technique,date, time, locational information, and combinations thereof, amongothers. Those of ordinary skill in the art will readily understand thatunique identifier 212 may be utilized to associate a device, such asdevice 100 or device 200, with any type of stored information, whereinthe unique identifier 212 itself may store said information, or whereinunique identifier 212 may comprise a sequence of digits and/or symbolsthat may be used to look up information stored in a collection ofinformation, whether electronic or not, separate from the device100/200.

FIG. 3A depicts a blood vessel sizing device 300 which may be similar inone or more aspects to one or more of devices 100 and/or 200 from FIG. 1and FIG. 2, respectively. Device 300 is shown as comprising a basestructure 302, wherein, in one example, base structure 302 may besimilar to base structure 102 and/or 202 from FIG. 1 and FIG. 2,respectively. Furthermore, device 300 has a scale 306, which may besimilar to scale 206 from FIG. 2.

In the example depicted in FIG. 3A, base structure 302 comprises asubstantially transparent (e.g. to light in the visible spectrum)polymeric material. Accordingly, this transparency may be utilized whenpositioning device 300 on an area of skin of a patient and/or othersurface (biological or synthetic) prior to an imaging procedure (e.g. anx-ray).

In one example, device 300 may comprise a perimeter area 304, whereinperimeter area 304 may represent an area of the base structure 302 towhich one or more of an adhesive layer or a deformable structure(described further in relation to FIG. 4 and FIG. 5) may be affixed. Inone example, that adhesive layer and/or deformable structure (notpictured) affixed to perimeter area 304 may be opaque to light in thevisible spectrum and/or spectrum of wavelengths utilized by an imagingprocess. In one implementation in which the perimeter area 304 is opaqueto light in the visible spectrum, perimeter area 304 encloses a window308 of base structure 302, wherein that area of base structure 302designated as window 308 remains substantially transparent to light inthe visible spectrum. As such, window 308 facilitates visual positioningof device 300 on an area of interest prior to an imaging procedure whileperimeter area 304 is substantially opaque. In certain embodiments, theperimeter area may be opaque with respect to only one of (a) light inthe visible spectrum and (b) spectrum of wavelengths utilized by animaging process to capture the target object or target area.

It will be readily apparent to those of skill in the art that whileperimeter area 304 is depicted in FIG. 3A with a particular shape, manyalternative shapes for perimeter area and/or window 308 may be realizedwithout departing from the scope of this disclosure. Furthermore, inanother example, perimeter area 304 may cover substantially the samearea as base structure 302, and without departing from the scope of thisdisclosure.

FIG. 3B depicts a device 340, wherein device 340 may be similar todevice 300 from FIG. 3A. Similarly to device 300, device 340 may have asubstantially transparent base structure 342. Furthermore, basestructure 342 may have a perimeter area 344, wherein perimeter area 344represents an area to which one or more of an adhesive layer and/or adeformable structure may be affixed. Accordingly, perimeter area 344 maybe substantially opaque to light in the visible spectrum. As such,visual placement of device 340 on an area of interest may be facilitatedby a substantially transparent window 348. It is noted that window 348,and similarly for window 308, while being substantially transparent tolight in the visible spectrum, include radiopaque scales 346 and 306,wherein scales 346 and 306 may be substantially opaque to light in thevisible and/or x-ray spectrum, among others.

In one example implementation, device 340 comprises a tab structure 350,wherein tab structure 350 may be an area of base structure 342 that isnon-adhesive. As such, structure 350 may facilitate removal of device340 from an area to which device 304 he was adhered prior to an imagingprocedure. An adhesive layer may be positioned on the entirety of orjust a portion of the

FIG. 4A schematically depicts a side view of an imaging device 400,similar to devices 100, 200, and/or 300 (wherein FIG. 1, FIG. 2, andFIG. 3A-3B depict plan views of devices 100, 200, and/or 300). As such,device 400 comprises a base structure 402 having a front surface 404 anda back surface 406. A scale 408, which may be similar in one or moreaspects to scales 206 and 306, is positioned on the front surface 404 ofbase structure 402. As previously described scale 408 may be printed,adhered, welded, or joined by any other means known to those of ordinaryskill in the art to a surface, such as the front surface 404. Thethickness of base structure 402 is represented as thickness 412, andwhich may be, in one example, 0.25 mm, 0.5 mm, 0.75 mm, or 0.9 mm, andthe like.

Turning to FIG. 4B, device 400 from FIG. 4A is depicted having analternative configuration, and including an adhesive layer 410 on theback surface 406 of base structure 402. In one example, adhesive layer410 may cover the entire surface area of the back surface 406 of basestructure 402. In another example, adhesive layer 410 may only partiallycover the back surface 406. Specifically, in one example, adhesive layer410 may cover an outer perimeter area, such as perimeter area 304 fromFIG. 3A.

It will be readily apparent to those of skill in the art that adhesivelayer 410 may comprise any known adhesive. In one example, adhesivelayer 410 may comprise a medical adhesive configured to temporarily andremovable bond a structure, such as device 400, to an area of skin of apatient.

FIG. 5A schematically depicts device 500. In one example, device 500 maybe similar in one or more aspects, to devices 100, 200, 300, and/or 400previously described. Accordingly, device 500 may comprise a basestructure 502, which may be similar to one or more aspects describedherein of base structure 102, 202, 302 and/or 402. A scale 504 may bepositioned on a front surface 503 of base structure, and a deformablestructure 506 may be positioned on a back surface 505 of base structure502.

As such, a front surface 513 of deformable structure 506 may be adheredto the back surface 505 of base structure 502 by any methodology knownto those of ordinary skill in the art, and including, but not limitedto, adhesion, molding, fastening, and/or welding, among others.Additionally, an adhesive layer 508, similar to adhesive layer 410, maybe positioned on part or all of a back surface 515 of deformablestructure 506. It should be understood that deformable structure 506 andadhesive layer 508 may be the same layer. Therefore, discussion of adeformable structure or adhesive layer should be interpreted as a singlelayer that has both properties.

Deformable structure 506 may comprise a material with physicalproperties (e.g. hardness) allowing for deformation (compression, andthe like) without failure of the material. Accordingly, deformablestructure 506 may comprise a sponge-like material which may be asynthetic foam, or any other material with mechanical propertiessuitable for deformation. Furthermore, in one example, deformablestructure 506 may have a thickness 514 of 1 mm, 2 mm, 5 mm, 10 mm, 15mm, among others.

FIG. 5B schematically depicts device 500 adhered to an uneven surface510. As such, deformable structure 506 is depicted in a compressedstate, wherein the back surface 515 of deformable structure 506 conformsto the undulations of uneven surface 510, while the front surface 513 ofthe deformable structure 506 remains substantially planar. Accordingly,base structure 502 of device 500, in addition to the radiopaque scale504 thereon, also remain substantially planar while device 500 isadhered to uneven surface 510.

FIG. 6A schematically depicts a radiographic image 610 resulting fromelectromagnetic radiation of a certain wavelength (or range ofwavelengths), e.g. x-rays, incident on a device 601 which may be laidover a passageway of a living being, such as a blood vessel of a human.Accordingly, device 601 may be similar in one or more of the aspectsdescribed herein to one or more of devices 100, 200, 300, 400, and/or500. In particular, FIG. 6A schematically depicts a source 608 emittingelectromagnetic radiation that is incident upon a base structure 602, aradiopaque scale 604, and a location marker 606 of device 601. In oneexample, part, or all, of the electromagnetic radiation incident onscale 604 and location marker 606 is absorbed. Yet, other embodimentsmay have materials that get excited or otherwise react to the imagingprocess or other process used in conjunction with the imaging process.Accordingly, the radiographic image produced upon detection of theelectromagnetic radiation transmitted through base structure 602includes a radiopaque scale image 612 and a location marker image 614.

FIG. 6B depicts the same device 601, but angled, at angle 607, withrespect to source 608 along a defined plane. Those skilled in the artwill appreciate that the device may be angled with respect to the sourcealong multiple planes, however, for sake of understanding aspects of theinnovative embodiment, only a single plane is discussed. Because thedevice 601 is angled with respect to the source, the electromagneticradiation emitted from source 608 is no longer orthogonal to basestructure 602 (electromagnetic radiation now incident upon basestructure 602 at an angle of (90°-[angle 607]°)). As such, theradiographic image 620 produced as a result of the angle between theincident radiation and device 601 results in a radiopaque scale markerimage 624 and a location marker image 622 having ellipsoidal shapes, asdepicted.

The distortion of the radiopaque scale marker image 624 and locationmarker image 622 may be regarded as an error of parallax, wherein, amongothers, minor axis 627 of radiopaque scale marker 624 no longerrepresents a true length. However, due to the concentric-circle designof scale marker 604 (e.g. radiopaque concentric-circle elements 104a-104 h from FIG. 1), the resulting radiopaque scale marker image 624includes at least one true length. In particular, the true length ofconcentric-circle elements 104 a-104 h is represented in radiopaquescale marker image 624 along the longest axis (major axis) 626 of thatellipsoidal image of radiopaque scale marker 624. As such, a user maydetermine the longest axis of radiopaque scale marker image 624, andmeasure one or more true lengths of one or more concentric-circleelements 104 a-104 h along said axis 626. In this regard, although thereare two axes shown (626 and 627), those skilled in the art will realizethat any straight line that passes through the center of a concentriccircle can serve as an axis. In this regard, the closest axis to thetrue axis may be set to the nearest degree, of the circle, or nearesthalf degree or whole number of degrees. Advantageously, device 601, andin particular, the concentric-circle elements 104 a-104 h, thereby allowa user to avoid errors of parallax.

In one example, device 601 may not comprise a rigid structure. Inparticular, in one example, base structure 602 may bend in one or moredirections. For example, base structure 602 may substantially conform toone or more areas of curvature of the human body onto which it is afixed. As such, due to bending of base structure 602 along one or moreaxes, a resulting marker image 624 produced by source 608 may bedistorted along multiple axes. For example, distortion of marker image624 may result in a first major axis associated with the depicted 20 mm(which may be other dimensions, such as 30 mm or 3 cm) concentric circleof marker image 624 (e.g. circle 104 h from FIG. 1), and a second majoraxis associated with, in one example the 10 mm concentric circle ofmarker image 624 (e.g. circle 104 d from FIG. 1), wherein the first andthe second major axes are not parallel. As such, in one example, it maybe advantageous for a user to determine a concentric circle size, fromthose concentric circle sizes depicted in marker image 624 (e.g. 2 mm, 4mm, 6 mm, 8 mm, 10 mm, 14 mm, 16 mm, 20 mm, or 30 cm among others) thatmost closely matches a dimension of an imaged feature. In this way, auser may identify a first major axis in marker image 624 to be used inassociation with a first imaged feature, wherein this first major axisis a most accurate axis visible in marker image 624 having a dimensionthat is close to a dimension to be measured in the first imaged feature.Accordingly, a user may identify a second major axis in marker image624, due to distortion of marker image 624 as a result of bending ofbase structure 602 along one or more axes. As such, the second majoraxis may not be parallel to the first major axis identified.Accordingly, the second major axis may be a most accurate axis visiblein marker image 624 having a dimension that is close to a dimension tobe measured in a second imaged feature.

FIG. 7 schematically depicts a radiological image 700, that defined afield of view or target area including one or more biological features(which may include a target object. In particular, the image 700 of FIG.7 may be an angiogram. Those of ordinary skill in the art will readilyunderstand various methodologies for carrying out an angiogram, whichinclude, among others, use of contrast agents to view blood vessels, andthe like. Accordingly, any known technique for angiography or otherradiographic imaging may be employed with the systems and methodsdescribed herein, and without departing from these disclosures.Furthermore, image 700 may be computer-generated, or may be produced bythe detection of electromagnetic radiation (e.g. x-rays) by a film.

FIG. 7 depicts a plurality of blood vessels comprising at least aportion of the carotid artery 701, and one exemplary branching bloodvessel is labeled as vessel 702. In one example, it may be desirable toobtain one or more dimensions of biological features from a givenradiological image 700. Accordingly, in one example, one or moredimensions of a stenosis 704 may be obtained from radiological image700. In one implementation, a device, such as device 100, 200, 300, 400,and/or 500 may be positioned on a surface of interest, and within thefield of view of a radiological image to be produced. In one specificexample, a scale image 706 (which may comprise a plurality of elementsand symbols) may be included in a radiological image 700 produced. Assuch, one or more true dimensions of one or more biological features(e.g. a blood vessel width 708) may be determined using one or moreconcentric-circle elements of the unknown size (e.g. elements 104 a-104h from FIG. 1) of scale image 706.

FIG. 8 schematically depicts an imaging system 800. Specifically, system800 includes a computer 802 having a processor 804, in memory 806, andan interface 808. Computer 802 is further connected to a user interface820, a source 810, and a detector 816. It will be readily apparent tothose of ordinary skill in the art that connections between devices 802,820, 810, and/or 816 may be wired or wireless, and using any knownnetwork type and/or communication protocol. For example, communicationbetween one or more of devices 802, 810, 820, and/or 816 may be througha local area network (LAN), a wide area network (WAN), or the Internet,and using a communication protocol including one or more of theTransmission Control Protocol (TCP), the Internet Protocol (IP), or theUser Datagram Protocol (UDP), among many others.

Processor 804 may be a general-purpose central processing unit, or adedicated and specialized processing chip. Processor 804 may contain asingle processing core, or multiple cores acting in parallel, and thelike. Memory 806 may be volatile or persistent, and may include one ormore of read only memory (ROM), random access memory (RAM), a solidstate hard drive (SSD), or memory using optical disc media (CD, DVD, andthe like), among others. Interface 808 may comprise those hardwareand/or software components for connection of computer 802 to one or moredevices 810, 820, and/or 816 across a network. Furthermore, userinterface 820 may comprise one or more of a display and/or a controlinterface for receiving instructions from user. Source 810 may comprisea source of electromagnetic radiation (e.g. x-rays) suitable forradiographic imaging. Accordingly, detector 816 may comprise anelectronic detection device sensitive to electromagnetic radiationemitted from source 810, and such that the electromagnetic radiationreceived by detector 816 may be used to construct a digital image.

Element 814 represents an area of skin of a patient to be imaged usingsource 810 and detector 816. Positioned on said area of skin of apatient 814 is a blood vessel sizing device 812, wherein the device 812may be similar to one or more of those devices (100, 200, 300, 400,and/or 500) previously described. Accordingly, one or more features ofdevice 812, such as, for example, a radiopaque scale, such as radiopaquescale 408, may be included in a resulting image constructed by computer802.

In one example, a user of system 800 may identify a biological featurewithin a radiological image, wherein said image may be a real-timedigital image produced by computer 802 from data received from detector816. For example, a user may identify a one or more passageways (bloodvessels) and/or one or more objects within passage ways (blood clots),among others. In one example, it may be desirable for a user todetermine a true dimension of one or more biological features present inan image produced by system 800. Accordingly, a user may input one ormore instructions, via interface 820, identifying one or more biologicalfeatures of interest within an image produced by system 800, and visibleto a user at user interface 820. Subsequently, one or more identifiedfeatures of interest may be compared to an image produced by bloodvessel sizing device 812, wherein said image may be similar to a scale,such as scale 612 and/or scale 624, among others. As such, one or moreknown sizes/dimensions of said scales 612 and/or 624 may be compared tothe one or more identified features of interest, and a true dimensionmay be determined. Furthermore, it will be apparent to those of ordinaryskill that blood vessel size or device 812 is agnostic to the type ofimaging equipment used, in addition to the magnification and/or specificimage manipulation processes applied to the data detected by detector816.

In one example, a user may manually compare a length property of abiological feature visible within an image produced by system 800 to oneor more known dimensions of a radiopaque scale present within saidimage. For example, a user may measure a width of a blood vessel, asshown in an image produced by system 800, using a calipers. However, dueto the magnification/scaling and/or other image manipulation stepscarried out on the data received from detector 816, this length measuredby the calipers may not be a true dimension of the width of the bloodvessel. Accordingly, the user may compare the length measured by thecalipers to one or more concentric-circle elements (e.g. elements 104a-104 h from FIG. 1) visible within a radiopaque scale (e.g. radiopaquescale 612 and/or 624), and wherein the radiopaque scale is visiblewithin the same radiological image as the blood vessel of interest (e.gthe visible radiopaque scale 612 and/or 624 will have been subject thesame scaling and/or other image manipulation processes such that adirect comparison between the length measured with the calipers, and oneor more lengths from the radiopaque scale is still possible). In doingso, the user may compare the measured length from the calipers to themajor axis (e.g. as discussed in relation to FIG. 6B) of the radiopaquescale, and by comparison to one or more of the known dimensions of theconcentric-circle elements, determine a true dimension of the bloodvessel width. Furthermore, it will be readily apparent to those of skillthat any mechanical measurement device may be utilized for measuring alength property of a biological feature. For example, a user may utilizea ruler, measuring tape, or calipers, among many others.

In another example, one or more true dimensions of an identifiedbiological feature may be determined by an automated process. Oneexample of such an automated process is described in relation to FIG. 9.

FIG. 9 is a flowchart that may be implemented in the automaticdetermination of a true dimension of a feature captured in aradiological image (e.g., radiograph/x-ray). In one example, thedescription in FIG. 9 may be used in conjunction with imaging system 800from FIG. 8. Image data may be received from a detector, such asdetector 816 (e.g., block 902). In one example, this image data mayinclude information related to one or more biological features (tissues,organs, blood vessels, blood clots, and the like). A dimensionalproperty (e.g., a length property) of the one or more biologicalfeatures of interest within the received image data may be obtained(e.g., block 904, which may follow block 902).

In an example embodiment, block 904 may represent one or more processesto determine a length of one or more features within a radiologicalimage using an arbitrary length metric (e.g. a number of screen pixels,and the like). In this way, due to one or more scaling and/or otherimage manipulation processes carried out on the image data used tocreate the radiological image, a true dimension of the one or morefeatures is not readily known.

One or more elements from image data that correspond toconcentric-circle elements, such as those elements 104 a-104 h from FIG.1, may be identified (e.g., block 906). Block 906 may occur in theabsence of block 904. Those of ordinary skill in the art will readilyunderstand that any computer image recognition processes may be utilizedwith the one or more processes of block 906, and without departing fromthe scope of this disclosure.

Symbols, such as for example, 106 a-106 g and 107 a-107 g, may beidentified from the image data. This may occur before, during, afterand/or in absence of blocks 904/906. In accordance with furtherembodiments, a major axis of one or more identified concentric-circleelements may be determined, such as at block 910. In this way, and asdescribed in relation to FIG. 6B, a longest axis of a radiopaque scalemarker image, such as radiopaque scale marker image 624 from FIG. 6B,may be used to read known lengths of one or more concentric-circleelements 104 a-104 h without an error of parallax (and/or with astatistically significant reduction in an error of parallax.

A dimensional property (e.g., the length property) of a biologicalfeature may be compared to one or more dimensions (e.g., lengths) ofconcentric-circle elements along the determined major axis of aradiopaque scale marker image, such as radiopaque scale marker image624. Upon comparison of the determined length property of the biologicalfeature to the corresponding concentric-circle elements of the samelength (or interpolating/extrapolating from one or more known dimensionsof concentric-circle elements), a true dimension value may bedetermined. As such, the determined dimensional property (e.g., thelength) of the biological feature may be converted into a true dimensionvalue (e.g., block 914).

A true dimension value may be communicated to a user, such as via userinterface 820 from FIG. 8, which may occur at example block 916.

FIG. 10A schematically depicts an example implementation of device 1004being used. In particular, FIG. 10A schematically depicts device 1004positioned on a neck area of a human patient 1002. Accordingly, in oneimplementation, device 1004 may be similar to device 100, 200, 300, or400, and the like. Following from FIG. 10A, FIG. 10 B schematicallydepicts patient 1002 being imaged using imaging device 1010. As will beapparent to those of ordinary skill in the art from the foregoingdisclosures described herein, imaging device 1010 may be, among others,part of an x-ray device for performing an angiogram. In otherimplementations, device 1010 may be a part of an MRI device, a CTdevice, a myelogram device, a thermograph device, an MRN device, anultrasound device, and/or combinations thereof, among others.

Accordingly, as schematically depicted in FIG. 10B, imaging device 1010may image a region 1006 that includes both device 1004 and, in oneexample, blood vessel 1008. In one specific example, blood vessel 1008may be a carotid artery, among others.

FIGS. 11A-11D schematically depict various implementations of a devicethat may be utilized for locating an area of interest within aradiological image. In certain embodiments disclosed herein, the devicemay be used to locate or estimate the location of a feature or area ofinterest of: (1) a first image of a first area, wherein a first featureis captured under a first image criteria; and (2) a second image thatcomprises at least the same first area, wherein the same feature ispresent but not captured or captured to a less degree, under a secondimage criteria, Non-limiting examples are discussed in relation to FIGS.11A-11D. In one example, FIG. 11A depicts a radiological image 1100 thatincludes a scale image 1102, which may be similar to scale image 706,and generated as a result of one or more imaging processes of a device,such as device 100, and the like. Additionally, FIG. 11A depicts aschematic view of a blood vessel 1106 having a feature of interest 1104,which may be, in one example, a stenosis, and the like. Furthermore,FIG. 11A depicts a branching vessel 1108. In one example, vessel 1106and feature 1104 may be visible within an image (e.g., radiologicalimage) 1100 through use of a contrast agent. In this regard, FIG. 11Amay represent a first image of a first area, wherein the feature 1104may be a first feature that is captured under the specific capturingconditions, such as using a radiograph and contrast agent (or specifictype/dosage of agent).

FIG. 11B schematically depicts a radiological image 1140 that is similarto image 1100 from FIG. 11A. In particular, FIG. 11B schematicallydepicts scale image 1102 being utilized to locate a feature of interest1104. Specifically, a position of scale image 1102 may be noted relativeto feature 1104. Accordingly, those lines 1120 and 1122 may representimaginary lines, or visible lines depicted on an electronic interface(computer screen) or other representation of image 1140 (e.g. a printedcopy of image 1140, and the like) that may be traced out from the centerof scale image 1102, and delimiting of the ends of feature 1104 withinvessel 1106. For example, a user (a clinician or otherwise) viewingimage 1140 may note that a “top” end of feature 1104 corresponds to a “3o'clock position” at an outer concentric-circle element (that largest 20mm circular element depicted, which may be larger or smaller, including,for example, 30 mm or 3 cm), and delimited by line 1122. Similarly, theuser may note that a “bottom” end of feature 1104 correspondsapproximately to a “4 o'clock position” at the outer concentric circleof scale image 1102, and delimited by line 1120. As such, while vessel1106 and feature 1104 are visible in image 1140 through use of acontrast agent, noting a position of feature 1104 relative to scaleimage 1102 may allow said feature 1104 to be located without usingfurther contrast agent in subsequent images having a same field of view.

In furtherance of this example, those of ordinary skill in the art willreadily understand various contrast agents, otherwise referred to asradiocontrast agents, or contrast media, among others, may be used toimprove visibility of one or more blood vessels, and associatedfeatures, when imaged using x-ray-based imaging techniques. Accordingly,in one example, a contrast agent may be utilized in image 1100 to viewvessel 1106, and may include an iodinated (iodine-based) contrast agent,among others. As such, those of ordinary skill in the art willunderstand that while contrast agents are generally considered safe foruse during in vivo imaging, there exist various side effects that may beassociated with the use of contrast agents. For example, contrast agentsmay have a detrimental impact upon kidney function, or may, in someinstances, lead to higher rates of blood clotting, among others. Assuch, it may be desirable for an imaging process to reduce an amount ofcontrast agent utilized to, in one example, image a vessel forpositioning of a stent, among others. Thus, a second image (which may bea subsequent frame in a live video capture) may be the same area andfeature (e.g., feature 1104), however, blood flow has moved the contrastagent, and as such, feature 1104 may be less visible or not visible.

FIG. 11C schematically depicts scale image 1102 being utilized to locatea feature within a vessel 1106 without using contrast agent. As such,respective to FIG. 11A, FIG. 11C may be considered a second image thatcomprises at least the same first area, wherein the same feature ispresent but not captured or captured to a less degree, under a secondimage criteria (e.g., no or less contrast agent). In one embodiment, atleast a portion of the vessel itself may be the feature that is lessvisible or not visible in the second image (or any image that is not thefirst image). In particular, an outline of vessel 1106 is depicted inFIG. 11C, having a first side wall 1110, and a second sidewall 1112.However, sidewalls 1110 and 1112 outlining vessel 1106 are included forclarity within radiological image 1150. As such, sidewalls 1110 and 1112represent one or more lengths of blood vessel 1106 that were previouslyvisible within the radiological image 1140 from FIG. 11B through use ofa contrast agent, but which may no longer be visible, or may havediminished visibility, within radiological image 1150 due to an absenceof a contrast agent. As such, it may be assumed that sidewalls 1110and/or 1112 of the vessel 1106 are not clearly visible withinradiological image 1150 in accordance to one embodiment. However, havingnoted the position of feature 1104 (which also may not be visible or isof reduced visibility relative to scale image 1102 from FIG. 11B), lines1120 and/or 1122 may be utilized to locate, approximately, feature 1104(from FIG. 11B) within image 1150. As such, lines 1120 and/or 1122 maybe utilized to position, in one example, a stent, at the feature ofinterest 1104 from FIG. 11B, and without using, or using a reducedamount of a contrast agent. Turning to FIG. 11D, stent 1130 may bepositioned in image 1160 relative to scale image 1102, and utilizingthat relative positioning noted using lines 1120 and/or 1122, and thelike. Specifically, stent 1130 may be moved into an area of vessel 1106(vessel 1106 may not be clearly visible within image 1160 due to absenceof contrast agent, and the like) by positioning relative to lines 1120and 1122.

Those of ordinary skill in the art will understand that images 1100,1140, 1150, and/or 1160 may be still images, or may be “live” imagesthat are periodically updated. In one example, one or more of saidimages may be updated as a frame rate of six frames per second, howeverthose of ordinary skill in the art will understand that anyupdate/refresh rate may be utilized without departing from the scope ofthese disclosures. Additionally, those of ordinary skill in the art willunderstand that's images 1100, 1140, 1150, and/or 1116 may be generatedusing any appropriate imaging technology including, among others,computed tomography and/or radiography, among many others.

Aspects Of The Present Disclosure

Aspects of the subject matter described herein may be useful alone or incombination with one or more other aspect described herein. Withoutlimiting the foregoing description, in a first aspect of the presentdisclosure, a blood vessel sizing device includes a marker configuredfor placement on the skin of a patient, the marker defines asubstantially circular shape and includes a plurality of radiopaquesubstantially concentric circles.

In accordance with a second aspect of the present disclosure, which canbe used in combination with the first aspect or any one of aspects twoto twenty, the blood vessel sizing device includes an adhesive foradhering the device to the skin of the patient.

In accordance with a third aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,the blood vessel sizing device includes a plurality of differentradiopaque symbols, wherein each of the plurality of differentradiopaque symbols represents a diameter of one of the plurality ofconcentric-circle elements.

In accordance with a fourth aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,each of the radiopaque symbols is a geometric shape.

In accordance with a fifth aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,each of the radiopaque symbols are numbers.

In accordance with a sixth aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,each of the plurality of radiopaque concentric-circle elements has adiameter, the diameters ranging from 2 mm to 12 mm.

In accordance with a seventh aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,each of the plurality of radiopaque concentric-circle elements includesat least three radiopaque substantially concentric circles.

In accordance with an eighth aspect of the present disclosure, which canbe used in combination any one or more of the preceding aspects, the atleast three radiopaque substantially concentric circles have diametersof about 6 mm, 8 mm, and 10 mm.

In accordance with a ninth aspect of the present disclosure, which canbe used in combination with any one or more of the preceding aspects,the plurality of radiopaque concentric-circle elements includes at leastfour radiopaque substantially concentric circles.

In accordance with a tenth aspect of the present disclosure, which canbe used in combination with the fifth aspect, the at least foursubstantially concentric circles have diameters of about 4 mm, 6 mm, 8mm, and 10 mm.

In accordance with an eleventh aspect of the present disclosure, whichcan be used in combination with the fifth aspect, the at least foursubstantially concentric circles have diameters of about 14 mm, 16 mm,18 mm, and 20 mm.

In accordance with a twelfth aspect of the present disclosure, which canbe used in combination with the twelfth aspect, the plurality ofradiopaque symbols are at least one of (i) geometric shapes, and (ii)numbers.

In accordance with a thirteenth aspect of the present disclosure, whichcan be used in combination with any one or more of the precedingaspects, the diameters of the plurality of substantially concentriccircles range from about 2 mm to about 20 mm.

In accordance with a fourteenth aspect of the present disclosure, whichcan be used in combination with any one or more of the precedingaspects, a blood vessel sizing method includes placing a device having aplurality of radiopaque concentric-circle elements on the skin of apatient, imaging the blood vessel and the device, and comparing theimage of the blood vessel to the image of at least one of the pluralityof radiopaque concentric circle elements to determine a size of theblood vessel.

In accordance with a fifteenth aspect of the present disclosure, whichcan be used in combination with the fourteenth aspect, imaging the bloodvessel and the marker includes using an angiogram.

In accordance with a sixteenth aspect of the present disclosure, whichcan be used in combination any one or more of the preceding aspects,comparing the imaged blood vessel to the imaged plurality of concentriccircles to determine the size of the blood vessel includes measuring theimaged blood vessel and comparing the measured blood vessel to theimaged diameters of the plurality of radiopaque substantially concentriccircles.

In accordance with an seventeenth aspect of the present disclosure,which can be used in combination any one or more of the precedingaspects, measuring the diameter of the imaged blood vessel includesusing a mechanical instrument.

In accordance with a eighteenth aspect of the present disclosure, whichcan be used in combination any one or more of the preceding aspects, themarker includes a plurality of different radiopaque symbols, whereineach of the plurality of different radiopaque symbols represents adiameter of one of the plurality of concentric-circle elements.

In accordance with a nineteenth aspect of the present disclosure, whichcan be used in combination any one or more of the preceding aspects,comparing the imaged blood vessel to the image of at least one of theplurality of concentric circles to determine the size of the bloodvessel includes measuring the imaged blood vessel and comparing themeasured blood vessel to the imaged diameters of the plurality ofradiopaque concentric-circle elements and reading the symbols.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

I claim:
 1. A non-transitory computer-readable medium comprisingcomputer-executable instructions that when executed by a processor areconfigured to perform at least: receiving data corresponding to abiological feature present in radiological image data; determining adimensional property of the feature; identifying one or more elementsfrom the image data corresponding to a plurality of radiopaque,concentric-circle elements of a blood vessel sizing device positioned onan area of skin of a patient; identifying a dimensional property foreach of the identified one or more elements; determining a longest axisof the identified elements; comparing the determined dimensionalproperty to the identified one or more elements, along the determinedlongest axis; and converting the determined dimensional property into atrue dimension value for communication to a user.
 2. The non-transitorycomputer-readable medium of claim 1, wherein the processor is furtherconfigured to: identify one or more radiopaque symbols corresponding tothe one or more dimensional properties of the elements.
 3. Thenon-transitory computer-readable medium of claim 1, wherein the one ormore elements identified from the image data are located on a basestructure of a device located on the area of skin of the patient,wherein the base structure has a thickness of less than 1.0 millimeters.4. The non-transitory computer-readable medium of claim 3, furthercomprising computer-executable instructions that when executed by theprocessor, cause the processor to at least: after receiving datacorresponding to the biological feature present in the radiologicalimage data, removing a non-adhesive tab structure projecting from a sideof the base structure, for facilitating facile removal of the devicefrom the area of skin of the patient.
 5. The non-transitorycomputer-readable medium of claim 3, further comprisingcomputer-executable instructions that when executed by the processor,cause the processor to at least: uniquely identify the device by using aradiopaque unique identifier on the base structure.
 6. Thenon-transitory computer-readable medium of claim 5, wherein theradiopaque unique identifier comprises a machine-readable barcode. 7.The non-transitory computer-readable medium of claim 3, furthercomprising: after receiving data corresponding to the biological featurepresent in the radiological image data, removing a non-adhesive tab areaon a back surface of the base structure, for facilitating facile removalof the base structure from the area of skin of the patient.
 8. Thenon-transitory computer-readable medium of claim 3, wherein theradiopaque location marker has a surface area of between 18 and 22square millimeters.
 9. The non-transitory computer-readable medium ofclaim 3, wherein the base structure comprises a polymeric material. 10.The non-transitory computer-readable medium of claim 3, wherein the basestructure is substantially transparent to light with a wavelength in thevisible spectrum.